Traffic control method and structure



June 21, 1966 1-. M. NELSON 3,256,625

TRAFFIC CONTROL METHOD AND STRUCTURE Filed March 14, 1962 2 Sheets-Sheet 1 mmvron. 790/745 M50 June 21, 1966 T. M. NELSON 3,256,625

TRAFFIC CONTROL METHOD AND STRUCTURE Filed March 14, 1962 2 Sh ets-Sheet 2 W 1, We; sa 33 E15 13 Pig .LE

0 INV EN TOR.

76 0/VA5 M dqsm United States Patent 3,256,625 TRAFFIC CONTROL METHOD AND STRUCTURE Thomas M. Nelson, East Lansing, Mich. (10026 114th St., Edmonton, Alberta, Canada) Filed Mar. 14, 1962, Ser. No. 179,556 1 Claim. (Cl. 401) This invention relates to a traffic control method and structure and more particularly to a highly effective traffic sign which is configured so that visual perception thereof clearly indicates its selective applicability to persons viewing the sign from a predetermined limited approach sector while simultaneously indicating its nonapplicability to all other persons observing the sign exterior of the predetermined limited approach sector.

Traffic signs of the prior known art have utilized a flat surface upon which the traffic message or command is imprinted, painted or otherwise represented thereon. The message or command thus conveyed by the flat surface traffic sign is visible to all persons in front of the sign. The entire message or command imparted by such a sign is completely visible to all viewers in a substantially undistorted manner, regardless of Whether or not they are directly in front of the sign or off to either side. Because of this apparent non-selective applicability of a flat surface sign to all persons viewing it, a very definite disadvantage has always existed in its effective use as a traffic control device. Persons viewing flat surface signs from various side angles are never sure whether or not the sign applies to them. In keeping with the universal convention that a sign is positioned at right angles to the road to which it applies, a driver must make a determination of the physical orientation of the sign in relation to his lane of traffic in order to determine whether or not the sign applies to him.

In view of the fact that there is nothing about its color, lettering or geometric form that indicates whether or not a flat surface traffic sign applies to a driver in a particular traflic lane, the driver must determine whether or not a traffic sign has applicability to him solely by reference to the signs physical orientation to his lane of traflic. In trafiic situations such as those previously discussed, a driver cannot with certainty accurately determine that a Hat surface trafiic sign applies to him solely by reference to the physical orientation of the sign. This is due to the fact that a flat surface sign retains its symmetrical appearance even though viewed from a side angle. Further, the traffic control indicia on the surface thereof do not appear distorted when viewed from a side angle. Because of these facts, errors in response generally occur.

The problem is not critical at intersections involving two streets that are substantially perpendicular to each other. In such cases, persons viewing a trafiic sign clearly know that it applies to them because of its clear-cut right angle orientation with their particular traffic lane. However, the problem does become increasingly critical as the angle of intersection between two streets becomes more acute. This situation is further complicated at multiple intersections where a plurality of converging lanes of traffic are found.

In view of the fact that it is the physical orientation of the fiat surface sign to any particular lane of trafiic which determines its applicability to that lane, it becomes increasingly dificult in a multiple intersection situation for a driver to perceive the signs orientation to a particular lane and thus to decide whether or not the sign applies to him. Further, quite often a plurality of signs are mounted on a single post at a multiple intersection and are oriented thereon so that each applies to a different lane. Here again, the driver has difficulty in selecting the sign, if any, which applies to him.

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There is another area that should be mentioned where the use of a flat surface traffic sign has a large disadvantage. The advent of limited access superhighways has created a road system throughout the country which has a plurality of incoming and outgoing lanes joining or leaving the main arteries of traflic. These lanes join the main highways at a relatively small acute angle. It is extremely difficult for a driver to determine, in the short time interval involved, whether or not a traflic sign located at such junctions applies to traffic on the main traffic artery or to traflic on the incoming or outgoing lanes.

It is thus seen that fiat surface traffic signs, in certain trafi'ic situations, constitute ambiguous signaling devices. This ambiguity has resulted in accidents or near accidents and hence constitutes a definite safety hazard. In addition, such ambiguity has resulted in time-consuming traffic jams or other disruptions in the orderly flow of traffic. This same problem applies to fiat surface traffic control signs for pedestrians; The problem is readily apparent at multiple corridor intersections in large buildings.

As will be hereinafter discussed, tests have shown that accuracy of slant response is greater in the case of a curved or otherwise modified traffic sign as opposed to a flat surface traffic sign. Therefore, use of a curved or otherwise modified traffic control sign in such traffic situations would eliminate this undesirable ambiguity.

A need has therefore existed for a unambiguous traffic sign for use at intersections which would enable a driver to determine, quickly and with accuracy, whether or not the sign applied to him.

A need has also existed for a traffic sign which would provide a driver with indicia, other than actual physical orientation of sign, by which to determine its applicability to him.

It is therefore an object of this invention to provide a traffic sign which virtually eliminates ambiguity in use at multiple intersections or at intersections and junctions wherein an acute angle of intersection is found.

Another object of this invention is to provide a curved traflic sign which selectively imparts an undistorted appearance and command only to certain critically positioned observers from among all that are able to view the sign.

A still further object of this invention is to provide a traffic sign which provides additional indicia of applicability to a particular lane of traffic other than its mere physical orientation to that lane of traffic.

Yet another object of this invention is to provide a traffic sign in which the message or command imparted thereby is entirely visible in an undistorted manner only to the particular lane of traffic or approach sector to which it is intended to apply.

Still another object of this invention is to provide a traflic sign wherein the shape of the sign appears to become increasingly distorted as the side angle from which it is viewed is increased.

Another object of this invention is to provide a traffic sign having traffic control indicia thereon which appear distorted or are not visible in part when viewed from a side angle.

Another object of this invention is to provide a trafi'lc sign whose shape and/ or message imparted thereby ap pears distorted to all persons viewing the sign except to i the persons for whom the signs message or command is In the drawings:

FIGURE 1 is a top view of the invention showing the use of a curved surface traflfic sign.

FIGURE'Z is a top view of a flat surface sign of the type now in universal use.

FIGURE 3 is a front elevation view of the curved surface traffic sign as viewed from a position directly in front of the sign.

FIGURE 4 is an elevation view of the flat surface trafiic sign as viewed from a postion directly in front of the sign.

FIGURE 5 is an elevational view of the curved surface traffic sign as viewed from a side angle and illustrating the apparent distortion of the overall shape of the sign of the traffic control message indicia thereon.

FIGURE 6 is an elevational view of the fiat surface traffic sign as viewed from the same side angle as that in FIGURE 5 and illustrating the absence of apparent distortion in the overall shape of the sign and of the message indicia thereon.

FIGURE 7 is an elevational view of the curved surface trafiic sign as viewed from a side angle greater than that of FIGURE 5 and illustrating the greater apparent distortion in the overall shape of the sign and the disappearance of a portion of the message indicia thereon.

FIGURE 8 is an elevation view of the flat surface traffic sign as viewed from the same side angle as that in FIG- URE 7 and illustrating the apparent absence of distortion in the overall shape of the sign and the full representation of the message being conveyed by the sign.

FIGURE 9 is a schematic view of a plurality of traffic intersections illustrating the possible ambiguities that confront a driver in determining to which lane of traffic a particular trafiic sign applies.

FIGURE 10 is a top view of a modification of the instant invention consisting of a two frontal surface angular slgn.

FIGURE 11 is a front elevation view of the sign shown in FIGURE 10 as viewed from a position directly in front of the sign and illustrating the lack of distrotion of the message indicia thereon.

FIGURE 12 is an elevational view of the sign shown in FIGURE 10 as viewed from a side angle and illustrating the apparent distortion of a portion of the message indicia thereon.

FIGURE 13 is a top view of another modification of the instant invention consisting of a multi-surface accordian type angular sign.

FIGURE 14 is a front elevation view of the sign shown in FIGURE 13 as viewed from a position directly in front of the sign and illustrating the lack of distortion of the message indicia thereon.

FIGURE 15 is an elevational view of the sign shown in FIGURE 13 as viewed from a side angle and illustrating the apparent distortion of alternate portions of the message indicia thereon.

FIGURE 16 is a top view of still another modification of the instant invention consisting of a plural curve serpentine type sign.

FIGURE 17 is a front elevation view of the sign shown in FIGURE 16 as viewed from a position directly in front of the sign and illustrating the lack of distortion of the message indicia thereon.

FIGURE 18 is an elevational view of the sign shown in FIGURE 16 as viewed from a side angle and illustrating the apparent distortion of alternate portions of the message indicia thereon.

General description In general, a trafiic sign is provided having tratfic control indicia provided thereon. The surface of the traflic sign is configured so that the shape of the sign and the appearance of the traffic control indicia provided thereon do not appear distonted when viewed from a position substantially in front of the sign. However, when the instant sign is viewed from a side angle, the overall shape of the sign and the traffic control indicia thereon appear distorted. In essence, a trafiic sign is thus provided which enables the viewer to determine with greater accuracy and speed whether or not a traffic sign applies to him.

Flat surface signs that are now in universal use permit ambiguities to arise in actual use situations which result in errors by drivers viewing the signs. The possibility of error is further compounded by such variables as weather, visibility, rate of speed of the vehicle, and-the physical condition of the driver as to eyesight and reaction time. Other national and international agencies have experimented with shape, color and content of traffic signs in order to develop optimally unambiguous signaling devices. However, the question has been overlooked as to how well the driver is able to localize the position of one type of sign as compared to another.

Inasmuch as a trafiic sign is usually visible to drivers on more than one road at an intersection, some means had to be developed in order to enable a driver to quickly and accurately determine whether or not a sign applied to him. Heretofore, the driver's perception of the tratfic signs actual physical orientation to his lane of trafiic has been the only factor in determining whether or not he would comply with the command imparted by the sign. This has not been satisfactory.

Laboratory studies were conducted in order to compare the accuracy of slant responses made to an'ordinary fiat surface traffic sign with those made to an experimental traffic sign having a curved surface. The results of these laboratory studies indicated that curved traffic signs were much superior to fiat signs. Fewer errors in driver response were found to occur when curved traffic signs were utilized. Drivers responding to curved signs were significantly less apt to brake their automobiles when the curved sign is not intended for them than is the case when the sign is flat. Further, slant perceptions of curved si'gns more nearly matched actual physical inclination of the signs. This was not the case with the flat surface signs. The use of flat signs thus created ambiguities which resulted in errors in driver response.

Such ambiguities in any signaling device result in increased hesistancy, uncertainty, and difliculty of response. The ideal traffic sign would seem to be that requiring the least time and attention to produce the required response. By these criteria, curved signs were found to be clearly superior to the flat signs now in use throughout the world.

The basic reason for the superiority of curved signs is the fact that they appear to change shape rapidly with slight changes in inclination. A curved sign has a symmetrical shape when viewed from a position directly in front thereof, but appears to have a distorted shape when viewed from an angle.

Thus, in an actual use situation, a curved traffic sign and the tratfic control indicia thereon will appear to have a distorted shape when viewed from a road or trafiic lane other than that to which it applies. On the other hand, a flat surface sign will still appear to have a symmetrical shape even though viewed from an angle. The trafiic control indicia thereon will also appear free from distortion.

As stated previously, the use of flat surface traffic control signs creates many ambiguities as used at intersections and on ingress and egress lanes of superhighways. A hypothetical road intersection complex embodying some typical trafiic situations faced by drivers today is shown in FIGURE 9. As dictated by present universal convention, the trafiic signs shown in FIGURE 9 are positioned at right angles to the road or lane to which they apply. Thus, signs 21 and 36 apply to lane 22, sign 23 applies to lane 24, sign 25 applies to lane 26, sign 27 applies to lane 28, sign 29 applies to lane 30, and sign 31 applies to lane 32.

As shown by dotted lines representing lines of vision, the driver of car A, B, C, D, E or F would have more than one traffic sign within View as he was approaching an intersection. The driver of car A in lane 22 would have to decide whether traflic sign 21, 23 or 36 applied to him. The driver of car B would also have to decide whether sign 21, 36 or 23 applied to him. An error on the part of either driver could result in a collision between the two cars. Further, a sudden and unexpected brakingof either car due to compliance with the wrong sign could result in ramming from the rear by other cars following in the same lane.

Similarly, the driver of car C would have to decide whether sign 23 or 25 applied to him. The driver of car D would have to decide whether sign 29 or 31 applied to him. The driver of car E would have to decide between sign 27 and sign 31. The driver of car F would have to decide between sign 27 and sign 29.

It should be pointed out that even though no errors actually occurred, indecision on the part of the driver as he approaches such intersections generally results in the slowing down of the car. This in itself can result in a dangerous traflic situation on a high-speed highway.

Thus, it becomes readily apparent that the use of curved or modified surface traffic signs would help solve some of the many problems facing drivers on our overcrowded highways.

Specific description More specifically, the instant invention consists of a traffic sign having a curved or contoured surface. As shown in the top view of FIGURE 1, the sign 19 has a curved symmetrical configuration and is mounted on a post 19a. A flat surface sign could be modified so as to have curved side wing portions and thus achieve substantially the same configuration. When viewed from a position directly in front of the sign (or from the lane of trafiic or road to which it applies), the sign has a symmetrical appearance and the traflic control indicia provided thereon have a full and even appearance. This is clearly shown in FIGURE 3 of the drawings. However, when the curved sign is viewed from an angle, the curved sign takes on the appearance of having an irregular shape and the traffic control indicia thereon appear distorted. For instance, FIGURE 5 illustrates the curved sign when viewed at from an angle of approximately 22 degrees from the lane of trafiic to which it applies. This would be the way the sign would appear to a driver approaching 'the intersection on a converging road to which the sign did not apply. It is noted that the right side of the sign appears to be cut off and the letter P appears to be narrower than the rest of the letters. Thus, even when the angle of intersection between two roads is very acute (22 degrees), the driver on the road to which the sign does not apply can quickly tell from the distorted ap pearance of the sign that the sign does not apply to him.

FIGURE 7 illustrates a curved traflic sign when viewed from a side angle of approximately 55 from the lane of tratfic to which it applies. It will be noted in this case that the sign appears to be cut approximately in half and the letter P is not visible. In addition, the letter O is partially deleted from view. Thus, the driver viewing the sign from this angle can quickly and easily tell that the sign does not apply to him.

In order to further explain the ambiguities that arise in the use of a fiat surface sign, FIGURES 2, 4, 6 and 8 have been placed adjacent to FIGURES 1, 3, 5 and 7, respectively. This gives a direct comparison between a flat surface sign and a curved sign when viewed from the same angle. FIGURE 2 is a top view of a flat surface sign 20 of the type now in universal use as a traffic control device. The flat surface sign 20 is mounted on a post 20a. FIGURE 1 is a top view of a curved surface embodiment of the instant invention.

FIGURE 4 is a front view of the flat surface sign as it appears when viewed from the lane of traffic to which it applies. FIGURE 3 is a view of the curved surface sign as seen from the lane to which it applies. It should be noted that when viewed from this position, both signs have identical symmetrical appearances and the trafiic control indicia thereon also appear to be free from distortion. Hence, both signs would be equally as effective when viewed from the lanes to which they apply.

FIGURE 6 is a view of the fiat surface sign as it appears when observed from a side angle of 22 degrees. It should be noted that the flat surface sign still appears symmetrical and the traffic control indicia thereon are not distorted. Hence, an error could occur in that a driver on an intersecting road might think that the sign applied to him. On the other hand, as shown in FIGURE 5, the curved sign, when viewed from the same side angle of approximately 22 degrees, clearly indicates by its apparent distortion its inapplicability to the observer. The side angle observer of the curved sign does not have to try to determine the physical orientation of the sign in relationto his road in order to make his decision. The apparent distortion of the sign and of the traffic control indicia thereon quickly indicates to him that it does not apply to him.

The superiority of the curved traffic sign over the fiat surface sign is again shown by comparison of the two types of signs when viewed from a side angle of approximately 55 degrees. As shown in FIGURE 8, the flat surface sign, even when viewed from a side angle of 55 degrees, still retains a substantially symmetrical appearance'an-d the message indicia thereon appear substantially free from distortion. On the other hand, as shown in FIGURE 7, the curved sign gives a distorted appearance when viewed from the same side angle of 55 degrees.

Further, the message indicia thereon are distorted and partially obscured. A driver observing the flat surface sign as shown in FIGURE 8 would, under certain conditions, still have trouble in determining the actual physical orientation of the sign to his lane of traffic. Hence, he could make an error as to whether or not the sign applied to him. It is highly unlikely that such an error could be made if a curved traflic sign were utilized.

Although the preferred embodiment of the instant invention has been shown and described as a curved sign, it is possible to achieve similar results by use of signs having two or more frontal surfaces provided with traffic control indicia thereon. Some examples of this are shown in the top views of FIGURES 10, 13 and 16.

One embodiment is the angular two frontal surface sign 33 mounted on post 3311 as shown in the top view of FIGURE 10. As shown in FIGURE 11, when the sign in FIGURE 10 is viewed 'by a driver to whom the sign applies, the trafiic control indicia thereon do not appear distorted. However, as shown in FIGURE 12, the foregoing sign and the traflic control indicia thereon would appear distorted when viewed froma side angle as in the case of an observer approaching on an intersecting road. More particularly, the portion of the traffic control indicia located on the sign surface facing away from the observer would appear distorted. In this case the letters OP would appear narrower than the letters ST. This apparent distortion would immediately make the driver cognizant of the fact that the sign did not apply to him.

The accordian type sign 34 and serpentine type sign 35 shown in FIGURES 13 and 16, respectively, illustrate other embodiments of the instant invention. As shown in FIGURES 14 and 17, the trafiic control indicia provided on the various surfaces of the signs appear free from distortion as if they were positioned on a fiat surface sign. A driver observing the signs as they appear in FIGURES 14 and 17 would know that they applied to him. However, as shown in FIGURES 15 and 18, the tratfic control indicia on the signs would in part appear distorted when the signs were viewed from an angle. The traffic control indicia which are positioned on the surfaces of the sign slanted away from the observer would appear narrower and somewhat distorted. Thus, the letters T and P would appear narrower than the letters S and O. This is clearly shown in FIGURES 15 and 18. A driver observing these apparent distortions would immediately know that the sign did not apply to him or to his lane of trafiic. Additional apparent distortion could be introduced into the signs shown in FIG- URES 11, 14, 17 by changing their overall outer configuration from that of a square or rectangular shape to some other symmetrical overall outer configuration such as a diamond shape.

It is also intended to be within the scope of the invention to provide a corrugated sign surface having trafiic control indicia thereon. The depth and angle of the corrugations of such signs could be varied so that alternate strip portions or strip segments of the traflic control indicia would not be visible if the sign were viewed from a side angle. This would also indicate to a side angle observer that the sign did not apply to him.

It is thus seen that a unique trafiic sign is provided having a curved or otherwise modified frontal surface configuration so as to effectively eliminate the ambiguities that accompany the use of flat surface signs.

It should be pointed out that although the curved sign appears distorted when viewed from a side angle so as to virtually eliminate errors in response, the degree of distortion is not such that would prevent an observer vto whom the sign did not apply from realizing that a controlled intersection was being approached. This has ,also been proven by actual experimentation.

Various modifications of the invention may be made without departing from the principle thereof. Each of these modifications is to be considered as included in the hereinafter appended claims unless these claimsby their language expressly provide otherwise.

Having thus set forth the nature of my invention, I claim the following:

A method of controlling trafiic approaching at an intersection formed by at least two lanes of traffic forming an acute angle 'therebetween, the steps which include:

(a) placing a sign having traffic control indicia thereon adjacent said intersection, and

(b) adjusting said sign for frontal viewing from one lane only, said traffic sign having a horizontally transversely curved frontal surface, said indicia being horizontally arranged on said surface, said trafiic sign having a symmetrical outer peripheral configuration which cooperates with the transverse curvature of said traffic sign so as to impart an asymmetrical distorted appearance to said traffic sign to all but frontal viewers of said sign whereby only frontal viewers of the undistorted sign are controlled by said sign.

References Cited by the Examiner UNITED STATES PATENTS 6/1875 Blowney 40l25 7/1888 Coote 40-137 4/1931 Dyment 40137 X 8/1937 Rous 40137 7/1939 Fonda 40l25 FOREIGN PATENTS 1/ 1953 France.

1905 Great Britain. 11/ 1927 Great Britain. 3/1930 Great Britain.

EUGENE R. CAPOZIO, Primary Examiner.

EDWARD H. F. ROSS, Assistant Examiner. 

